In an exhaust system for a motor vehicle, low-frequency air-column resonance sound that occurs in a tail pipe having a relatively long actual length is a factor of worsening exhaust booming noise. Thus, measures have been taken to reduce the air column resonance sound such as by providing a sub-muffler in series with a main muffler.
Patent Document 1 describes a configuration in which a perforation is provided in a position at a distance from an outer end of a conduit for conveying exhaust gas from an internal combustion engine, in order to attenuate resonance in the conduit.